Machines for applying closures to containers are well known and widely used. The present invention relates to the application of threaded closures to containers having threaded necks, and is particularly directed to the application of closures to containers which hold consumable liquids.
One of the major difficulties with most currently used equipment, closures and containers, is the need to thoroughly and frequently clean the equipment so that the contents of the containers is not contaminated. In addition, problems associated with so-called "cocked" or misaligned threads on the closure and container neck are also prevalent. Further, operators of bottling facilities also experience difficulty resulting from crushed containers resulting from the application of excessive downward forces in the capping operation. Overtightening or stripping of the threaded connection between the closure and the container is also a problem and, depending upon the lubricity of the liquid being placed in the container, stripping can be a significant problem.
Many bottlers, for convenience and to reduce costs associated with shipment of empty containers, blow mold containers on-site. Because many bottlers do not have expertise in blow molding operations and, in particular, tooling maintenance, serious problems can arise, such as bottles being molded to configurations which significantly vary over time. In some instances, bottlers have other difficulties relating to the quality of their bottles, such as excessive flash, mismatching of mold components, excessive parison pleating, and non-round openings. While caps are generally molded to relatively precise and consistent dimensions, blow molded bottles generally are not, particularly bottles made on-site by bottlers. To provide a reliable closure on bottles of varying dimensions and quality is a difficult challenge for cap suppliers.
The system of the present invention includes a capping apparatus with a simplified spindle assembly which may be easily cleaned. Turning of the spindle assembly is accomplished by causing its upper end to engage with a magnetically controlled rotation inducing gear segment or rack. The invention includes a variety of alternative devices for holding or gripping a cap and transferring rotative forces from the spindle to the cap. For example, a resilient ring or disk may be used to grip the cap by its splines or knurls and releasably turn the cap into engagement with the container neck. Alternatively, a chuck with opposing spring loaded jaws may be used.
The spindle assembly of the present invention has particular application in turret-type capping equipment of the general type shown and described in U.S. Pat. No. 3,771,284, but the spindle assembly and related rotation inducing equipment could be used in other types of machinery. When used with turret-type machinery, the feeder assembly of the present invention is used to bring a cap into initial proximity to a moving container neck. A conveyer brings the container into engagement with the cap and delivers the container to a turret. The container support of the turret holds the container in vertical alignment with a spindle assembly. When the container support engages a cam, rotation of the turret causes the container to be lifted into engagement with the spindle assembly. The spindle assembly has a chuck carried by the lower portion of the spindle, which grips the cap.
When the turret rotates, the spindle assembly comes into engagement with a rotation inducing surface which causes the spindle and the cap to rotate for a predetermined rotational extent. The cap gripping portion of the spindle assembly is designed to prevent overtightening of the cap onto the container. In one embodiment of the present invention, resilient fingers are carried by a ring held within the lower portion of the spindle assembly. If the cap tightens before the spindle assembly stops rotating, the resilient fingers allow the ring to continue rotating while the cap has stopped rotating. In an alternative embodiment, a cap gripping chuck with spring loaded jaws releasably grip the cap when the container is lifted into engagement with the spindle assembly. Again, if the cap tightens onto the container neck before the spindle disengages from the rotation inducing surface, the spring loaded jaws slip past the splines on the cap to prevent stripping of the cap.
To further prevent overtightening of the cap onto the container, the rotation inducing gear segment or rack is releasably held in place by a magnet. When a predetermined force is applied laterally to the gear segment or rack, the retaining force of the magnet is exceeded and the gear segment or rack is free to pivot, thereby preventing further rotative forces from being applied to the cap.
It should be also be noted that the caps and container necks of the present invention are specifically designed to facilitate the placement and tightening operations of the apparatus of the present invention. In particular, the cap of the present invention includes a skirt with a generally conical or tapering inside surface. In a preferred embodiment, the thickness of the skirt varies so that the inside diameter of the skirt is larger at the lower end as compared to the inside diameter of the skirt at its upper end. Similarly, the outside surface of the vertical portion of the threaded neck of the container is tapered such that the outside diameter of the neck at the uppermost portion is less than the outside diameter of the neck at the lower portion of the neck. The matching conical configuration of the inside of the cap and the container neck facilitate the initial placement of the caps on the container neck. Thus, the incidence of misalignment (or "cocking") of the threads on the cap and container neck is reduced substantially. This improved or increased interfitting tolerance of the cap onto the bottle neck over overcomes some of the difficulties resulting from "out-of-tolerance" blow molded bottles.
These and other objects and advantages of the present invention will be better understood upon a reading of the following specification read in conjunction with the accompanying drawings.